1 files changed, 89 insertions, 0 deletions
diff --git a/include/block/export.h b/include/block/export.h
new file mode 100644
index 0000000000..7feb02e10d
--- /dev/null
+++ b/include/block/export.h
@@ -0,0 +1,89 @@
+/*
+ * Declarations for block exports
+ *
+ * Copyright (c) 2012, 2020 Red Hat, Inc.
+ *
+ * Authors:
+ * Paolo Bonzini <pbonzini@redhat.com>
+ * Kevin Wolf <kwolf@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef BLOCK_EXPORT_H
+#define BLOCK_EXPORT_H
+
+#include "qapi/qapi-types-block-export.h"
+#include "qemu/queue.h"
+
+typedef struct BlockExport BlockExport;
+
+typedef struct BlockExportDriver {
+    /* The export type that this driver services */
+    BlockExportType type;
+
+    /*
+     * The size of the driver-specific state that contains BlockExport as its
+     * first field.
+     */
+    size_t instance_size;
+
+    /* Creates and starts a new block export */
+    int (*create)(BlockExport *, BlockExportOptions *, Error **);
+
+    /*
+     * Frees a removed block export. This function is only called after all
+     * references have been dropped.
+     */
+    void (*delete)(BlockExport *);
+
+    /*
+     * Start to disconnect all clients and drop other references held
+     * internally by the export driver. When the function returns, there may
+     * still be active references while the export is in the process of
+     * shutting down.
+     */
+    void (*request_shutdown)(BlockExport *);
+} BlockExportDriver;
+
+struct BlockExport {
+    const BlockExportDriver *drv;
+
+    /* Unique identifier for the export */
+    char *id;
+
+    /*
+     * Reference count for this block export. This includes strong references
+     * both from the owner (qemu-nbd or the monitor) and clients connected to
+     * the export.
+     */
+    int refcount;
+
+    /*
+     * True if one of the references in refcount belongs to the user. After the
+     * user has dropped their reference, they may not e.g. remove the same
+     * export a second time (which would decrease the refcount without having
+     * it incremented first).
+     */
+    bool user_owned;
+
+    /* The AioContext whose lock protects this BlockExport object. */
+    AioContext *ctx;
+
+    /* The block device to export */
+    BlockBackend *blk;
+
+    /* List entry for block_exports */
+    QLIST_ENTRY(BlockExport) next;
+};
+
+BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp);
+BlockExport *blk_exp_find(const char *id);
+void blk_exp_ref(BlockExport *exp);
+void blk_exp_unref(BlockExport *exp);
+void blk_exp_request_shutdown(BlockExport *exp);
+void blk_exp_close_all(void);
+void blk_exp_close_all_type(BlockExportType type);
+
+#endif